Well, six months after installing my new engine, I'm still having some drivability issues.

A little background:
Block and head are out of a '78 Volare. It's got the 270 Erson cam, SI oversize valves, and an iron super six intake. The carb is an OEM Holley 2300 off of an unknown 70's Ford product that I picked up off of E-Bay. This carb has the reverse idle adjustment screws. I rebuilt the carb approximately a year ago. This is the first time it has been installed. It has a genuine Holley electric choke kit installed, and is adjusted as rich as it is designed to be set.

The problem:
The engine will drop as much as 900-1000 RPM if you put it in gear before it warms up, and be very difficult to drive. After warming up, the RPM drop is only around 200 RPM. Furthermore, at ~600 RPM (no load idle) there is a very distinct whistle. The whistle is very hard to locate by ear (I'm half deaf), but cupping my hands over the top of the carb makes it go away, not get worse.

Attempted solutions:
After spraying carb cleaner (and even starting fluid) everywhere I could even concievebly think of there being a vacuum leak, I still couldnt' find one. I went ahead and removed and re-installed the intake manifold again, hoping that might solve the problem anyway. The problem remains unchanged, and I'm am now fairly certain that I dont' have a vacuum leak anywhere at the manifold. The idle screws are adjusted as rich as they will go, and I have 15 inches of vacuum. I called the Erson tech line, and the tech said that I should be very happy with that vacuum reading; he has the same cam in his wife's car and only gets 11" at idle. I feel though, that if I could adjust the carb richer, I would gain more vaccuum, as it increased steadily until the adjustment screws bottomed out.

Questions:
Is it possible that this carb was designed to run lean, and is simply unsuited to my engine. If so, can that be remedied by modification, or would I be better off just giving up on it and finding an aftermarket 2300? Or is there something else that I have overlooked that would cause similar problems?

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Used to own:
'82 Dodge D150
Erson 270 Cam, O/S valves, mild port work, ~9.5:1 compression

Currently fighting with an '85 VW Cabriolet

My other passion

Yes, it's the carb. Yes, it's too lean. Get a conventional Holley 2300 and you'll be much better off.

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Joshua

There is a debate going on at my local speed shop, but no one's "anted" up yet...the shop owner and a few Holley diehards say you can swap the metering block out on the 2300 for a regular mix/screw block and make it "normal" not "smog"...I'm kind of leary since the way the reverse screw block works is a bit different from the normal block....

Anybody else know the answer on this one (it could save CStryker a few bucks and swap blocks)...

-D.Idiot

Sounds like the hot idle compensator valve. This is a little doohickey that is basically a bi-metallic spring attached to a rubber stopper on the air horn of the carb. I used to have a 78 Mercury Zephyr station wagon with a 302 and the carb would whistle from this little valve.

I don't think you need the choke adjusted all the way rich. It sounds to me like you have a vacuum leak. Check the adapter you are running. I have seen a couple that were cast really poorly and actually had holes in the casting. Check all the gaskets as well.

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Casually looking for a Clifford hyperpak intake for cheap.

I had a carb that had a whistle to it, idle was lousy. Tried another carb, gave me a satisfactory idle. I think the first carb had an internal vacuum leak.
There are several metering block gaskets for the 2300, maybe you have the wrong one installed.

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Slant Cecil

Well, I'm sure there's no bi-metallic spring in the air horn, however, there is a loosely fitting tube that goes into the air horn. I had assumed it was originally designed to hook up to a crankcase breather or some such thing, instead of creating provisions in the air cleaner housing. It's currently capped off, but I guess it's possible that it's sucking air around the sides of it.

I know the choke shouldn't /have/ to be adjusted way rich, but it' runs much better that way. As I said, I had been blaming a vacuum leak for the past 6 months, but no matter how hard I look, I just can't find one. I inspected the adapter plate very carefully when I did the manifold swap and replaced all the gaskets between the carb base and the head (including EGR).

Cecil, at this point, finding an internal leak sounds like it might be my last chance to save this carb. This weekend I guess I'll have to take it off and tear it all the way down again to see if I missed something when I rebuilt it.

DusterIdiot, regarding metering block changes, I do have a 600 CFM four barrel vacuum secondary carb that I'm not using at the moment. Assuming the metering block swap is possible at all, should a 2300 and a four barrel have the same (or similar enough) metering block? I assume not, mainly because the 4 barrel has a transfer tube to feed the secondaries, but it's a thought. I would just tear them down and compare them this weekend, but the 4 barrel is at home, 180 miles away. The bad thing about college is that there's not a whole lot of room to store your spare auto parts.

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Used to own:
'82 Dodge D150
Erson 270 Cam, O/S valves, mild port work, ~9.5:1 compression

Currently fighting with an '85 VW Cabriolet

My other passion

I used to have a 2300 off an early 80's mustang (80179?)...The economaster venturies were perfect for a stock slant..sadly the idle circuit was lean and I ended up drilling the block to bandaid the situation....
The "tube" you have used to hook to some solenoid for the Ford, I just pulled it off and capped it...if you have a leak at the base plate/throttle shaft then we have a problem...

Holley's are modular, so in essence you can swap the primary metering block off a 4160 (say 1850-1/etc...), as long as it doesn't use a tranfer tube to the secondary block that is internal (older versions run through the throttle body)...You can essentially just grab the block and swap it, on the 2300 (use the 2300 bowl...)...


This kind of swap started the primary question a few weeks back at the speed shop, the idle circuit in the normal Holley meters the air to fuel emulsion in the idle circuit...in the reverse idle circuit the mixture is "fixed" if I remember right and turning the screw just adds more "air fuel mix" rather than "just adds more fuel"... If we can swap an old Holley 600 normal block on the smog 2300 and make it "normal" then this adds some new ideas for getting Holley 2 barrels with the Economaster Boosters that have better signal and atomization than the standard leg boosters.


With that being said, if you are using a Mr.Gasket 1937 and super six for this conversion (or even a 2 barrel conversion plate on an offy intake)...make sure to check the surfaces for leaks...the 1937 conversion usually needs the plate "doped" to the intake with RTV, and the allen screws doped over once installed as the bolt holes may expose the outside to the intake well with the wrong type of gasket....


Good luck, been there, got a bald spot because of that...

-D.Idiot